As a result order gasex 100caps with mastercard, the oxi- can transfer electrons together with hydrogen and have unique roles in the genera- dized carbon has fewer H atoms or tion of ATP from the oxidation of fuels buy cheap gasex 100caps. Other oxidation-reduction coenzymes work gains an O atom. The reduction of a com- with metals to transfer single electrons to oxygen. Vitamin E and vitamin C (ascor- pound is the gain of electrons, which shows bic acid) are oxidation-reduction coenzymes that can act as antioxidants and protect in its structure as the gain of H, or loss of O. The different functions of oxidation-reduction In the oxidation of lactate to pyruvate (see Fig. The carbon atom with the coenzyme has a unique functional group that accepts and donates electrons and is keto group is now at a higher oxidation state specific for the form of electrons it transfers (e. A different portion of the coenzyme binds the enzyme. Like activation- between carbon and oxygen are counted as transfer coenzymes, oxidation-reduction coenzymes are not good catalysts without belonging to oxygen, whereas the two elec- participation from amino acid side chains on the enzyme. The coenzyme nicoti- The catalysis of oxidation-reduction reac- namide adenine dinucleotide (NAD ) is synthesized from the vitamin niacin (which tions is carried out by a class of enzymes called oxidoreductases. A subclass of oxidore- forms the nicotinamide ring), and from ATP (which contributes an AMP). The ADP ductases is given the common name dehy- portion of the molecule binds tightly to the enzyme and causes conformational drogenases (such as lactate dehydrogenase), because they transfer hydrogen (hydrogen atoms or hydride atoms) from the substrate to Lactate Pyruvate an electron-accepting coenzyme, such as NAD. COO– COO– Dissociates as H+ H O C H C + + CH3 CH3 O H O C NH2 C NH2 + O N N – O Nicotinamide R O P 2 H H H H HO OH O NH2 C N N C CH AMP provides additional HC C N binding interactions N – which induce O P O 2 conformational changes NAD+ in the enzyme O H H R = H H H + O HO OR NADP R = P O– O– Fig. NAD - dependent dehydrogenases catalyze the transfer of a hydride ion (H:) from a carbon to NAD in oxidation reactions such as the oxidation of alcohols to ketones or aldehydes to acids.